Primary cementing in a cased oil, gas, or water well is the process of placing cement in the annulus between the casing and the formations through which the wellbore passes. The major objective is to provide zonal isolation, which is the prevention of fluid flow between different formation layers. Various materials may be added to the cement to enhance the performance and/or to improve the economics. Recent development of heavy oil reserves using heat (for example using steam) have placed additional stresses on the cement sheath, which may compromise the zonal isolation achieved with existing cement slurries.
Current cement composites that contain extenders that also provide set cement flexibility are not stable at the high temperatures at which steam is used in some heavy oil recovery wells. Extenders that can provide flexibility after extended exposure to high-pressure steam would be desirable.